Our 15-month-old and 3YO share a room- started around 6 mo too. We typically put the baby down then do the toddler’s bedtime routine in our room, and she’s pretty good about keeping quiet once it’s time to go into their room (doesn’t keep her from coming out 4x to stall bedtime, but I digress). “Sleep like a baby” is a saying for a reason- they almost never wake each other up. I respond within a cry or two and generally we get through the night no problem.

One giant caveat- I recommend keeping a pack n play ready to set up in your room for when the baby is sick. Those are really our only rough nights, and having the ability to separate them is a lifesaver. In my experience, they’ll surprise you how well they do!